It has been the general practice to utilize skirt boarding on conveyors to provide a seal between the moving conveyor belt and the stationary bin, or chute, where material is discharged onto the belt. This point is important to seal because it is here that a great percentage of the dirt encountered throughout a plant finds its source. Skirting has also been utilized along edges of a conveyor belt unrelated to a hopper. Material escaping from the conveyor becomes scattered throughout the plant and represents a loss of the material conveyed as well as a safety hazard.
Prior skirt boards were constructed from resilient material, such as rubber or the like, and were mounted by some means which afforded manual adjustment, in an effort to mate the board with the conveyor belt in some such manner as might form an adequate sealing relationship. The seal was difficult to maintain because of the wear on the lower edge of the skirt board resulting from the abrasion by the constantly traveling conveyor belt which made the frequent adjustments required, almost impossible for maintenance personnel in the plant to cope with. Unless the adjustment was attended to at regular intervals it was not possible to prevent the material from escaping from the conveyor system.
Conventional skirt board installations heretofore have provided arrangements where it was possible to adjust the skirt boards to obtain a sealing engagement with the conveyor belt but generally, these prior skirt boards were bolted in place and it became a major operation to perform the adjustments. The system had to be completely shutdown, the bolts loosened, the skirt boards adjusted and then the bolts retightened. This operation ha to be repeated frequently.
Various camming arrangements have also been used in which an overcenter toggle mechanism secures the skirt against a backing plate. When adjustment is required the toggles are loosened, the skirt sections lowered and the toggle reclamped. See for example the arrangements illustrated in U.S. Pat. Nos. 2,593,610 and 3,499,523, British Pat. Nos. 1,256,691 and 1,378,509 and West German Pat. Nos. 1,931,845 and 2,416,963. In systems such as these which utilize moving parts for adjustment the parts soon become inoperative due to corrosion and the build up of material. Often the skirt board operates in highly contaminated environments. If the skirt sections are clamped with insufficient force the belt can force the skirt board upwardly opening the leak and allowing material to escape. In order to prevent upward movement a high clamping force was required but such a force prevented any downward adjustment of the skirt board.
The assignee of the present application developed a skirt board and mounting arrangement for interlocking skirt board sections which utilized, in one embodiment, vertical slides on a mounting plate mating with grooves in a skirt board and arranged to facilitate movement of the skirt board sections in a downward direction but to resist upward movement. This arrangement is illustrated in U.S. Pat. No. 4,236,628 reissued as Re No. 31,249.
None of the prior art arrangements incorporate the features of the present invention.